Regarded as the key driver of ultra-dense optoelectronic circuitry, single-molecule sensing, and ultrahigh-density data storage, nanoscale lasers have attracted much attention. The development of nanoscale lasers is rapidly advancing and a variety of approaches have been explored, including Fabry-Perot lasers, whispering gallery lasers, photonic crystal lasers, and metallic lasers. Recently, plasmon lasers with both physical size and optical mode confinement below the diffraction limit of light in a different number of dimensions have been demonstrated using localized surface plasmons bound to metal surfaces. With the ability to generate intense electromagnetic radiation at the nanoscale in femtosecond timescales, plasmon lasers now stimulate the exploration of broad scientific and technological innovation at the nanometer-scale.